Functional neuromuscular electrical stimulation (FNS) to restore control over deficient muscular functions has been used as a clinical treatment of motor deficiencies for the last 20 years (Hambrecht, F. T., Reswick, J. B., (eds): Functional Electrical Stimulation: Application in Neural Prostheses. New York N.Y., Marcel Dekker, 1977). Applications include respiratory assistance by stimulation of the diaphragm in quadriplegic patients, and neuroprosthesis of the arms and legs (Hambrecht, F. T., Reswick, J. B., (eds): Functional Electrical Stimulation: Application in Neural Prostheses. New York N.Y., Marcel Dekker, 1977; Mortimer, J. T.: Motor prostheses, in Brooks (ed): Handbook of Physiology, the Nervous System. Motor Control, Bethsda, Md., 1984 Am Physiol. Soc. 2:155-187; Salmons, S. and Vrbova, G. 1969 J. Physiol. 201:535). Some of these studies have indicated that changes in muscle function occur based on the stimulation. It is known that muscle fiber composition and resulting physiologic and metabolic characteristics (force, contraction and relaxation times) depend on neural activity (Salmons, S. and Vrbova, G. 1969 J. Physiol. 201:535). By electrically controlling nerve and muscle activation, improved fatigue-resistance of atrophic, paralyzed muscles in quadriplegic patients has been reported (Peckham, H. et al. 1976 Clin. Orthop. 114:326.)
In most FNS applications, electrical stimulation is applied to muscles in situ to restore or supplement function. Recently, researchers have evaluated the use of FNS to control the function of heterotopically transferred skeletal muscles. In some cases, the muscle may perform or work very differently from its original function. Dynamic cardiomyoplasty is a procedure in which a skeletal muscle graft is applied to the myocardium and trained to contract in synchrony with the heart muscle (Chachques, J. C., et al. 1988 Circulation 78:203 (Suppl 3); Acker, M. A., et al. 1987 Science 236:324; Magovern, G. J., et al. 1988 Ann Thorac. Surg. 45:614). The first clinical cardiomyoplasty was performed in 1985 (Carpentier, A. and Chacques, J. C.: 1985 Lancet 1:1267). In the approach followed by those investigators, the latissimus dorsi muscle was conditioned to behave like a cardiac muscle by slowly increasing muscle work to adapt to a new cardiac-like function. It is estimated that over 100 cardiomyoplasties have been performed world-wide and may represent an important role in the treatment of congestive heart failure.
In the 1960's the concept of the application of functional electrical stimulation in urology began to emerge. Direct bladder surface stimulation was attempted in order to induce micturition by a patient. However, many clinicians became disenchanted because the high current required would spread to the pelvic floor mixture, causing pain and contraction of the external sphincter during micturition. Device failure was common and a fibrocapsule often developed around the bladder electrodes (Alexander, S. and Rowan, D., 1968 Br. J. Surg., 55:358; Boyce, W. H., et al. 1964 J. Urol., 91:41; Merrill, D. C. 1974 J. Urol. 112:823; Merrill, D. C. and Conway, C. J. 1974 J. Urol. 112:52; and, Timm, G. W. and Bradley, W. E. 1969 Invest. Urol. 6:562).
Throughout the 1970 and 1980's, research toward bladder stimulation was directed toward sacral anterior root stimulation in conjunction with selective or complete sacral deafferentation (Brindley, G. S. et al. 1986 J. Neurol. Neurosurg. & Psychiatry 49:1104; and, Tanagho, E. A. et al. 1989 J. Urol. 142:340). Sacral anterior root stimulation requires intact sacral motor roots and a detrusor capable of contraction.
The use of the rectus muscle to assist manual-compression bladder emptying has been reported (Zhang, Yu-Hai et al., 1990 J. Urol. 144:1194). A rectus muscle sling to suspend the bladder to a level immediately beneath the anterior rectus sheath was used, thereby allowing neurologically injured patients to empty their bladder with manual compression. The skeletal muscle flap has also been described for bladder augmentation. Direct anastomosis between skeletal muscle and the bladder wall will develop ingrowth and resurfacing of the muscle with transitional cells. Calculi and cartilaginous formation commonly occur however, complicating this technique (Buyukunal, S. N. C., et al. 1989 J. Ped. Surg. 24:586).
There is a need for an improved method of inducing micturition by an individual with an areflexic bladder. There is a need for methods of electrical muscle stimulation to induce micturition by an individual with an areflexic bladder.